Method and means for changing the clamping force at which and during each time a weft thread end is temporarily held during weaving on looms



July 8, 1952 E. PFAPRWALLER 2,602,472

METHOD AND MEANS FOR CHANGING THE CLAMPING 'FORCE AT WHICH AND DURING EACH TIME A WEFT THREAD' END I IS TEMPORARILY HELD DURING WEAVING ON LOOMS Filed June 7, 1947 3 Sheets-Sheet 1 ATTORNE E. PFARRWALLER METHOD AND MEANS FOR CHANGING THE CL.

2 72 .Tv du. uw 2 h 2 E e mm ms 3 G N .I P M A July s, 1952 AT WHICH AND DURING EACH TIME A WEFT THREAD END IS TEMPORARILY HELD DURING WEAVING ON LOOMS Filed June 7, 1947 INVENTOR fe W//v FA/PRWAL se ATTORNEY July 8, 1952 E PFARRWALLER 2,602,472

METHOD AND MEANS FOR CHANGING THE CLAMPING FORCE AT WHICH AND DURING EACH TIME A WEFT THREAD END IS TEMPORARILY HELD DURING WEAVING ON LOOMS 5 Sheets-Sheet 5 Filed June '7, 194'? INVENTOR few/N Ramen/AL L 5 e.

Patented July 8, 1952 METHOD AND MEANS FOR CHANGING THE CLAMPING FORCE AT WHICH AND DUR- ING EACH TIME A WEFT THREAD ENDVIS TEMPORARILY HELD DURING WEAVING N LOOMS Erwin Pfarrwaller, Winterthur, Switzerland, assignor to Sulzer lrx'es, Socit Anonyme, Winterthur, Switzerland Application J une 7, 1947, Serial No. l'253,228

17 claims. (ci.v 139-194) The invention relates toa method and to a device for carrying out the method, for making fabrics on gripper shuttle' looms, whereby at least one end of a weft thread inserted into the shed and projecting beyond the edge of the fabric, is temporarily held by means of a device for gripping and holding the thread.

In looms in which the weft threads are drawn by gripper shuttles from bobbins located outside the shed, the thread must be somewhat longer than the width of the fabric; the thread is cut after its insertion into the shed. The thread ends projecting beyond the edge of the fabric are held firmly by clamping devices, the so-called edge clamps, when being cut and/or when being detached from the shuttle, until they are beaten up by the reed and the shed is closed. These edge clamps seize the weft thread in the shuttle path and hold it until it is beaten up into the fabric. The clamping force must be suitably adjusted to prevent pulling of the weft thread end out of the edge clamp while the thread is beaten up by the reed and also after the beat-up, unless the clamps are fully released.

When forming selvages by tucking the thread ends projecting from the fabric into a following shed, too great clamping forces exerted by the edge clamp are undesirable, especially in the case of light fabrics, since they may cause breakage of the end of the weft thread or an incorrect taking over thereofl by thetucking needle. 'I'oo much tension in the weft threads causes the outermost warp threads to be drawn close to each other resulting in a selvage which is woven too tightly. Consequently, the fabric will be too narrow before reaching the temples and the latter cannot function properly, at least as far as the warp threads of the selvage are concerned, i. e. hold the fabric stretched to the point of the shed so that the warp threads are parallel and in the direction of movement of the reed. This causes lateral friction between the warp threads of the selvage and the reed and chafing and weakening of the threads. Because of the broken weft thread ends and the excessively stressed warp threads, the selvage thus formed is not only weakened whereby further Working of the fabric is affected, but also suffers particularly as to appearance. y

It has been proposed to open the clamp for bending over of the thread ends by the tucking needle. Because of the elasticity of the weft threads their ends are liable to jump out of theclamp and are not taken hold of by the tucking needle,`or the bent-over end forms a loop outside of the fabrLe. This method produces an inaccurate tucking in of the weft thread ends.

It is an object of the present invention to pro-v vide an improved method which avoids the shortcomings set forth above and which is characterized by the fact that the force exerted for holding the weft thread end is changed during the operation of the loom.

Another object of the invention is the' provision of al weft thread end clamping or holding mechanism including means operative during normal Working of the clamp and changing the clamping pressure applied to the thread forholding its end while the thread is in the clamp.

Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and claims and shown in the drawings which, by way of illustration, show what I now consider to be preferred embodiments of my invention.

In the drawings:

Fig. 1 is a diagrammatic illustration of the cloth beam side of a loom equipped with a mechanism according to the invention;

Fig. 2 is a diagrammatic side view of the mechanism according to the invention for gripping and holding the weft thread and changing the holding pressure while the thread is in the clamp;

Fig. 3 illustrates a portion of the device shown in Fig. 2, in a different operating position;

Fig. 4 is a diagrammatic top view of a portion of the device according to the invention, includ-A ing a portion of a selvage produced according to the invention;

Fig. 5 is a diagrammatic illustration of a modified portion of the device according to the invention;

Fig. 6 is `a diagram showing the forces produced by the mechanism according to Fig. 5;

Fig. 7 is a diagrammatic showing of another modification of the device according to the invention; f

Fig. 8 is a diagrammaticishowing of a further modification of the device according to the in,l vention.

Like parts are designated by like numerals in all figures of the drawings.

Referring more particularly to Fig. 1 vof the drawings, numerals l and 2 designate lateral shields between and adjacent to which the following parts of the loom can be seen; the cloth beam 3 with wound up fabric 4, the main drive shaft 5 provided with clutch and brake 6, the motor 1, the reed 8, and the heddles 9.

The weft thread I0 is connected to the shuttle I2 and, drawn from bobbin II. The shuttle is projecteisbyethe picking mechanism I3 and runs along the picking path I4 and into the shuttle receiving device l5. Adjacent/fo the inner side of each of thewices I Land I5 is a mechanism I6 for gripping and-llding the weft thread I; a control device |1 supervises the arrival of the shuttle I2 in the receiving device I5 and stops the main shaft and the loom in known manner by declutching the shaft'from the motor 1 and braking the shaft, in case the shuttle arrives too late or not at all.

After insertion of the weft thread I0 the clamps I6 move from their rest position into lth-e picking path I4 of the shuttle and grip the weft thread and hold it adjacent the fabric 4 and maintain its tension during beating up by the reed 8. The weft thread III may be made of vegetable, animal, metallic or articially produced material. There may be only one clamp I6 and in that case the one adjacent the receiving box I5, or, if the fabric 4 is parted by weft thread cutters into several lengths while it is produced, additional clamps may be provided between always two lengths of material and adjacent the' weft thread cutters.

In the operating phase of the clamp shown in Fig. 2 the weft thread I0 has already .been inserted in the shed formed by the warp threads I'8. In the illustrated construction the clamp I6 is made in one piece with its drive rod I9, and its clamping portion which consists of a foot portion and a clamping jaw 2| which is movable in portion 2|), has j-ust been brought from its rest position i indicated by dotted lines, into position II which is in the path of the shuttle.

A cam shaft 22 which is positively driven by the main shaft 5 of the loom, is provided with a cam disc 23 which cooperates with the cam roller 24 of the bellcrank lever 25. The latter swings about stationary pin 26 and presses on .the needle member 28 which has a foot portion forming the jaw 2| with such force as to overcome the resistance produced by springs 29 and 30 and to hold the clamp 20, 2| in open position for receiving thethread I0. Rigidly connected to pin or needle 28 is a collar member 3| against which rests the compression spring 29. Member 3| has a forked extension 32 which embraces the needle 33 surrounded by a spring which rests on collar 34 and presses it to the extension 32.- Needle 33 is parallel to needle -28 and extends movably through rod I9 and a rearward extension of the foot portion 20 of the clamp member I6. Spring 29 is less strong than spring 30, exerting, for exampl-e one third of the pressure of spring 30 when the clamp 28, 2| is closed.

Another cam 35 which may be on the same disc as cam 44 or on an individual disc, operates lever 36 through roller 31. Lever 36 swings about stationary pin 38 and is articulated to rod I9 by means of pin 39. Rod I9 slides in guide 4|I and its free end reciprocates in a substantially straight line. Levers 25 and 36 are pulled together by a strong spring 4| and Vrollers l24, 31 are firmly pressed to their respective cams. For maintaining the width of the fabric 4, conventional temple rollers l42 are provided under a cover member 43.

The mechanism operates as follows: I

Shaft 22 rotates in the direction of the arrow shown in Fig. 2 and its cam 44 causes movement of roller 24 from position III to position IV, after weft thread I0 has been inserted into the shed I8.

4 Springs 29 and 30 are thereby freed to act on pins 28 and 33 and the-jaw portion 2| of pin 28 is pressed to thread I8 before it is released from the shuttle I2 or cut, whereby the tension in the thread is maintained.

Thereafter roller 31 and lever 36 are pressed to the right -by the carri 45 and the thread clamp I6 is moved to its rest position I shown in dotted lines in Fig.;2. Thread I0 is thereby carried close to the point of the shed I8 and can be beaten up -by the reed 8. Fig. 3 shows the position of the weft clamp relatively to its operating cam at this moment.

The shed is changed by alternating the heddles 9 for tucking the weft thread and I0a into the following'shed. During this time the pressure of the clamp on the thread is changed by returning bellcrank lever 25 from position IV into position III whereby cam 46 presses on auxiliary needle 33. T'his causes removal of collar 34 from abutment 32 and renders spring 30 ineffective. The clamping pressure depends now solely on spring '29 and amounts to one quarter only of what it is as long as spring 30 is effective too. Due to the reduced pressure the thread end Ilia can now be pulled out of the clamp without pulling together the warp threads which form the selvage. For this operation the thread end is taken hold of by the hook 48 of the tucking needle 41 which is reciprocated as indicated by the double arrow in Fig. 4. The needle may -be driven by shaft 22 for example as disclosed in Patent No. 2,185,308 of January 2, 1940.

The clamp I8 remains in the rest position I indicated in dotted lines in Fig. 2 until a new weft thread has been inserted into the shed I8.

Fig. 5 illustrates a modification of the variable pressure weft clamp according to the invention. In this case the clamp 49 comprises a tension spring 5| which interconnects the extension 32 with a similar extension which is attached to collar member 52 which is rigidly connected with -needle 53 taking the place of needle 33 of the modification shown in Figs. 2 and 3. Needle 53 has a second collar 54 which rests on the inside of rod I9 when full clamping pressure is exerted Fig. 6 is a diagram showing the clamping forces P at various operating phases of the device according to Fig. 5 in dependence on the stroke h of needle 53. When needle 53 is pressed down by cam 46. spring 5| is tensioned. If the depression amounts to the stroke h1 the force exerted by spring 5| amounts to P1 and the clamping force is reduced to R1. If needle 53 is pressed down by a distance h2 the force of spring 5| increases to Pz and the clamping force is reduced to R2. The tension force of the spring 5| at its maximum elongatii is equal or smaller than the force of compression spring 50 and the clamping force exerted on thel weft thread can be adjusted by the use of suitable springs and/or strokes to any desired value between zero and a maximum value Po. This is of great importance for weaving very light fabrics. For changing the influence of spring 5| it is merely necessary to change the position of cam 46 on arm 25. If it is moved upwards the stroke h of needle 53 and the effect of spring 5| are decreased, and vice versa.

In the modification shown in Fig. 7 one spring =56 only is used which tends to keep the clamp 20, 2| closed by acting with one end on collar 51. The other end of the spring does not rest on the inside of foot portion 2|) as in the. modifications described previously but rests on the fork 56 extending laterally from needle 59. The up per end 60 of ieedle 59 is bent toward the viewer of Fig. 'l over rail 6|. If the latter is lifted spring 56 is compressed.

l For gripping the weft thread I0 the clamp is in position II which is illustrated in Fig. '7. Cam 52 at the end of rod 25' which corresponds to the horizontal part of bellcrank lever 25 inFig. 2, is then moved from position II into position IV in the same manner as in the modification according to Fig. 2. Rail 6| is connected with a branch 25a extending from bellcrank lever 25' and is lifted simultaneously with cam 82. This causes lifting of needle 59 and compression of spring 56. When the clamp is moved towards the point of the shed, from position II to position I' as in Fig. 2, the horizontal pin end 60 slides on rail thereby maintaining the increased compression of spring 56. Shortly before the tucking-in operation of the weft thread end, bellcrank lever turns counterclockwise, back to position III. This causes lowering of rail 6I and pin 59 andrelease of .the compression of spring 5i.

For producing special effects, sometimes different threads: are used which are under diierent tension when inserted in the shed. In these cases it may be desirable to use different gripping forces for holding the different kinds of threads. Fig. 8 illustrates a mechanism whereby this can be accomplished. Instead of one cam member of the type shown in Fig. 2 or two cam members extending from the same lever as in Fig. 7, two cams 63 and 5l individually mounted on two individual levers |25 and |26 are pro-. vided as shown in Fig. 8. Cam 63 serves solely for opening the clamp 20, 2| for receiving a freshly inserted weft thread. Lever |25 on which cam 63 is mounted is equivalent to the elbow lever 25 in Fig. 2. Since there is second elbow lever |26. an additional cam must be providedon shaft 22. Cam 6l is mounted to lever |26. The device may be so arranged as to cause change of the clamping force, for example only at every other actuation of the weft thread holding device I6. or to control the clamping force to a different extent at different actuations of the thread holding device. Depending on how many different types of weft thread are used, shaft 22 makes only one half, or one third revolution, or less, for every pick and two, three, or more cams M are provided on disc 23 for opening the weft clamp at every pick.. The additional cam or cams on shaft 22 is or are of such conflguration as to assure the desired clamp pressures for the individual weft threads. If it is desired to clamp some of the weft threads at constant pressure and others at varying pressure, cams are provided for the other threads only.

The configuration of the running off surface a of cam M in Fig. 2 is so that the clamp pressure is reduced after the weft thread hasbeen beaten up and after the change of the'shed. The cam may be so shaped, i. e. its length reduced, as to decrease the clamping forcebefore the beat up, whereby the weft tension can be made different for different consecutively inserted weft threads. This. of course, calls for the provision of a plurality of different cams,

change the clamping force toa different degree at the different ends of one weft thread. Other variations along these lines can be accomplished by the devices according to the invention without departing from the scope of the present invention, for example reduction of the clamping force after the beat up, or change of the clamping force at different moments for different threads or at different sides of the fabric.

While I believe the above described embodiments of my invention to be preferred embodiments, I wish it to be understood that I do not desire to be limited to the exact details of design and construction shown and described, for obvious modifications will occur to a person skilled in the art.

In the claims:

l. In the-method of producing a selvage on a fabric woven on a loom by clampingly holding the end of a weft thread inserted in the shed and projecting therefrom, beating up theY weft thread, and tucking said end portion after the change of the shed back into the next following shed, the step of reducing, during the tucking operation, the clamping force by which the thread end portion is held.

2. In the method of producing a selvage on a fabric woven on a loom by holding the lend portion of weft threads inserted in the shed and projecting therefrom and bending said end portion back into the shed, the step of changing the force by which the thread end portion is held and substantially maintaining the changed force during the step of 'bending the end. portion of the thread back into the shed.

3. In a mechanical loom for weaving comprising warp threads forming a shed, a weft thread, and a shuttle picking the weft thread through the shed, a weftthread holding'device disposed outside the shed and movable substantially reciprooally and parallel to the warp threads, said device comprising pressure actuated weft thread .gripping means including pressure varying means,

moving means connected with said device, operating means contacting said' pressure varying means, and drive means actuating and common to said moving and operating means.

4. In a mechanical loom for weaving comprising warp threads forming a shed, a weftthread, and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising two individual spring means and weft thread gripping means actuatedby said spring means, a spring tensioning member contacting one of said spring means, and operating means in alternate intermittent contact with said gripping means and with said tensioning member.

5. In a mechanical loom for Weaving compris-M i. ing warp threads forming a shed, a wef`ttliread',g and a shuttle picking the weft thread through' the shed, a weft thread holding mechanismffpo sitioned at a side of the shed and comprising weft thread holding means having a springa thread gripping member connected withv said spring, a

spring tension control means, and actuating means contacting said gripping member and said control means at different instants.

6. In a mechanical loom for weaving comprising warp threads forming a shed, a weft thread, and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising weft thread holding means having a, spring, a thread gripping member connected with Said spring, a

.7 l spring tension control means, and actuating means adapted to individually operate y said gripping member and said control means.

7. In a mechanical loom for weaving comprising warp threads forming a shed, a weft thread,

, and a shuttle picking the \Weft thread through the shed,` a weft thread holding mechanism positioned at a side of the shed and comprising weft thread holding means having a spring, a thread gripping member connected with said spring. a

second spring connected with and stronger than A the first spring and adapted to augment its force. and spring tension control means connected with said second spring.

8. In a mechanical loom for weaving comprisl ing warp threads forming a shed, a weft thread,

and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising weft thread holding means having a spring, a thread gripping member connected with said spring, a second spring, means for connecting and disconnecting said springs with and from one another for augmenting and reducing the force of the -flrst spring, and means actuating said connecting means,

9. In a mechanical loom for weaving comprising warp threads forming a shed, a weft-thread, and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising a spring, a thread gripping member actuated by said spring, a second spring connected with said rst spring for augmenting its force, spring tension control @aus connected with said second spring, arid* actuating means contacting said gripping member and said control means at different instants.

10. In a mechanical loom for weaving comprising warp threads forming a shed, a weft thread, and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising a compression spring, a thread gripping member actuated by said spring, a tension spring connected with said rst spring, support means connected with said tension spring, and spring tension control means contacting said support means.

1l. In a mechanical loom for weaving comprising warp threads forming a shed, a weft thread, and a shuttle picking the weft thread through the shed, a weft thread holding mechanism positioned at a side of the shed and comprising weft thread holding means having a spring, a thread gripping member connected with said spring, spring tension control means, actuating means adapted to operate said gripping member, and other actuating means adapted to operate said control means.

12. In the method of producing a selvage on a fabric woven on a loom by clampingly holding the end portion of a weft thread inserted in the shed and projecting therefrom, beating up the weft thread, and tucking said end portion after the change of the shed back into the next following shed, the steps of maintaining the clamping force with which the weft thread is held during the beat up, of maintaining-a reduced clamping force during the tucking operation, and of fully releasing the clamping force thereafter.

13. In the method of weaving on a loom wherein an end portion of the weft threads inserted in the shed and laterally projecting therefrom is individually clampingly held during the beat up operation, the steps of changing the clamping pressure by which ythe end portion of a number of the threads is held while it is held, and of clamping the end portions of the other weft threads at constant pressure.

14. In a mechanical loom for weaving comprising loom operating means, warp threads forming a shed, a weft thread, a shuttle picking the weft thread through the shed, and a thread clamp for holding an end of an inserted weft thread including a spring for closing the clamp on the thread and clamp opening means connected with and actuated by the loom operating means for opening the clamp against the pressure of said spring: spring tension varying means connected with said spring and with said opening means for changing the pressure of said spring upon actuation of said opening means and while the clamp is closed.

15. The method of weaving a fabric on a loom comprising the steps of clampingly holding the end of a weft thread projecting from the shed after the weft thread has 'been inserted therein and at least during the time the weft thread is beaten up, and of changing the clamping force every time a weft thread is so clampingly held.

16. The method of weaving a fabric on a loom comprising the steps' of gripping, at full force, the end of a weft thread projecting from the shed after the weft thread has been inserted in the shed, beating up the weft thread, maintaining a gripping force on the thread at least during the beat up operation, and reducing the gripping force from full force to a fraction thereof during each period a weft thread is grippingly held.

17. The method of weaving a fabric on a loom comprising the steps of clampingly holding the end of a weft thread projecting from the shed after the weft thread has been inserted therein and at least during the time the weft thread is beaten up, and of changing the clamping force every time a weft thread is so clampingly held and at a dierent degree for different weft threads.

ERWIN PFARRWALLER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,948,051 Rossman Feb. 20, 1934 2,090,726 Golden Aug. 24, 1937 2,185,308 Pfarrwaller Jan. 2, 1940 2,389,808 Moessinger Nov. 27, 1945 

